Retrograde Group Research Articles

Doppler assessment of the aortic isthmus and perinatal outcome in preterm fetuses with severe intrauterine growth restriction

To evaluate the characteristics and association with perinatal outcome of the aortic isthmus (AoI) circulation as assessed by Doppler imaging in preterm growth-restricted fetuses with placental insufficiency. This was a prospective cross-sectional study. Fifty-one fetuses with intrauterine growth restriction (IUGR) and either an umbilical artery (UA) pulsatility index (PI) > 95(th) centile or a cerebroplacental ratio < 5(th) centile were examined at 24-36 weeks' gestation. AoI impedance indices (PI and resistance index) and absolute velocities (peak systolic (PSV), end-diastolic and time-averaged maximum (TAMXV) velocities), were measured in all cases and compared with reference ranges by gestational age. Furthermore, fetuses were stratified into two groups according to the direction of the diastolic blood flow in the AoI: those with antegrade flow (n = 41) and those with retrograde flow (n = 10). Clinical surveillance was based on gestational age and Doppler assessment of the UA, middle cerebral artery and ductus venosus (DV). Adverse perinatal outcome was defined as stillbirth, neonatal death and severe morbidity (respiratory distress syndrome, bronchopulmonary dysplasia, Grade III/IV intraventricular hemorrhage, necrotizing enterocolitis and a neonatal intensive care unit stay > 14 days). Adverse perinatal outcome was significantly associated with an increased AoI-PI (area under the curve 0.77; 95% CI, 0.63-0.92; P < 0.005). A significant correlation (P < 0.001) was found between retrograde blood flow in the AoI and adverse perinatal outcome, the overall perinatal mortality being higher in the retrograde group (70% vs. 4.8%, P < 0.001). In 4/5 (80%) fetuses the reversal of flow in the AoI preceded that in the DV by 24-48 h. AoI-PSV and AoI-TAMXV were < 5(th) centile in 40/51 (78%) and 48/51 (94%) cases, respectively, whereas AoI-PI was > 95(th) centile in 21/51 (41%) cases. Retrograde flow in the AoI in growth-restricted fetuses correlates strongly with adverse perinatal outcome. Absolute velocities in the AoI are decreased in growth-restricted fetuses. The data suggest a potential role for Doppler imaging of the AoI in the clinical surveillance of fetuses with severe IUGR, which should be confirmed in larger prospective studies.

Antegrade Versus Retrograde Titanium Elastic Nail Fixation of Pediatric Distal-Third Femoral-Shaft Fractures: A Mechanical Study

To determine whether the stability of elastic stable intramedullary nail (ESIN) constructs differ in terms of antegrade versus retrograde insertion for the fixation of pediatric distal-third transverse femoral-shaft fractures. Ten synthetic composite adolescent-sized femur models and 20 flexible titanium (Ti) intramedullary (IM) nails were divided into antegrade and retrograde groups. A simulated transverse fracture was created in each of 10 models in the distal-third region of the shaft (more precisely near the distal fifth). The fractures were then stabilized with ESIN. The specimens were subjected to four-point bending and then axial torsion. Flexural forces were applied to the medial aspect of the model across the fracture site at a rate of 0.05 mm/s to a maximum displacement of 3.7 mm (7 degrees). Torsional moments were applied to the distal aspect of the model in internal and external rotation at a rate of 0.75 degrees/s to a maximum of 10 degrees. Loads and stiffnesses were determined between consistent displacement limits; differences were compared using t tests (alpha = 0.05, two tailed). Flexural stiffness was significantly greater in the retrograde group (350 +/- 72 N/mm) compared with antegrade (195 +/- 95 N/mm; P = 0.02). A 66-kg load placed across the fracture displaced the site 3.7 mm for the antegrade group, whereas the retrograde group required a load 89% greater (125 kg). Although torsional stiffness tended to be greater in the antegrade group, the differences were not statistically significant (P = 0.2). Although the recommendation for distal-third femur fractures is antegrade nail insertion, this study demonstrates that given satisfactory cortical starting points in the distal fragment, retrograde insertion provides greater stability. These mechanical testing data are the first to address this specific fracture scenario and may aid surgical decision making.

The excision of right hemicolonic carcinoma with anterograde clearance to lymph nodes

To investigate the essentials of operation and the postoperative effect of right hemicolonic carcinoma with anterograde clearance of lymph nodes. One hundred and thirty-five patients with right hemicolonic infiltrated carcinoma, who were eligible for radical excision (D(3)), were divided into 2 groups. Among them, the anterograde clearance of lymph nodes was performed on 56 cases; the retrograde clearance was performed on 79 cases. Both groups showed no significant difference in age, sex, Dukes' staging and pathological type. The average time of operation: the anterograde group was (180 +/- 40) min; the retrograde group was (180 +/- 20) min. The average amount of bleeding: the anterograde group was (200 +/- 80) ml; the retrograde group was (200 +/- 30) ml. The cleared number of lymph nodes: the anterograde group were 6.3 +/- 4.2, 2.6 +/- 3.1, 1.5 +/- 2.3 in paracolon, middle and radicel of vasorum respectively, the total number was 11.4 +/- 8.6; the retrograde group were 6.4 +/- 2.2, 2.8 +/- 2.1, 1.1 +/- 1.1 respectively, the total number was 10.8 +/- 5.6 (P > 0.05). The postoperative metastasis to liver: the anterograde group was 8 cases (13.9%); the retrograde group was 21 cases (26.6%, P < 0.05). The 5-year survival rate: the anterograde group was 72.8% (41/56); the retrograde group was 65.5% (52/79) (P < 0.05). The operative technique of the excision was little difficulty and complexity, and it could fit well with the requirement of non touch isolation, and act to cut down the postoperative metastasis to liver and to elevate 5-year survival rate.

Is retrograde stenting more reliable than antegrade stenting for pyeloplasty in infants and children?

ObjectivesTo compare antegrade and retrograde internal double-J stenting for pyeloplasty drainage in children. The success of placing the stent in position and the complications were compared in both groups. MethodsBetween October 2001 and December 2004, 42 children with unilateral pelviureteral junction obstruction underwent pyeloplasty by a single surgeon. Antegrade and retrograde double-J stenting was attempted in 17 children (mean age 1.3 years) and 25 children (mean age 1.5 years), respectively. Antegrade stenting was attempted during the pelviureteral anastomosis, and the retrograde stent was placed just before the operation by cystoscopy. Fluoroscopy was not routinely used to confirm stent placement in either group. The stents were removed 4 weeks later at cystoscopy. ResultsSuccessful stent placement without malpositioning was achieved in 14 (82%) of 17 and 24 (96%) of 25 children, respectively, in the antegrade and retrograde groups. The cause of unsuccessful stenting in both groups was the inability to cross the ureterovesical junction. The mean time taken for retrograde stenting was 9 minutes (range 6 to 15). All children with successful stent placement by either technique were discharged within 72 hours after the operation. The hospital stay for children with unsuccessful double-J stent placement varied from 7 to 10 days. No stent malpositioning occurred with retrograde stenting; 1 child in the antegrade stent group had a malpositioned stent in the distal ureter, which was retrieved at ureteroscopy. ConclusionsIn our experience, retrograde double-J stenting seems more reliable than antegrade stenting for pediatric pyeloplasty, with greater success and lower complication rates.

Collisional Origin of Families of Irregular Satellites

A distinctive feature of the irregular moons of the giant planets is their orbital grouping. Previously, the prograde and retrograde groups of irregular moons at Jupiter were believed to be groups of fragments produced by the disruption of two large moons. More recently, we have shown that the retrograde group has not one but probably four or more parent bodies. We also found that fragments were launched from two of the four identified parent moons, producing two clusters of irregular moons with members of each group having similar orbits. Named the Ananke and Carme families, these two groups consist of seven and nine known member moons, respectively. The origin of this orbital clustering is unknown. Current rates of collisions among satellites in the retrograde group are too low to explain them. Collisions with cometary impactors are even less likely. Groups of irregular satellites with similar inclinations at Saturn are also yet to be explained. It is conceivable that the satellite families are remnants from early epochs of solar system formation when impactors were more numerous. In this paper we investigate the possibility that satellite families formed via collisions between large parent moons and stray planetesimals. We find that the Ananke and Carme families at Jupiter could indeed have been produced by this mechanism, unless the residual disk of planetesimals in heliocentric orbit was already severely depleted when the irregular satellites formed. Conversely, we find that formation of the Himalia group of prograde Jovian satellites by the same mechanism is unlikely unless a massive residual planetesimal disk was still present when the progenitor moon of the Himalia group was captured. We place constraints on the mass of the residual disk (1) when satellites were captured, and (2) when the Ananke and Carme families formed. These values depend sensitively on the assumed size-frequency distribution of planetesimals.

Orbital and Collisional Evolution of the Irregular Satellites

The irregular moons of the Jovian planets are a puzzling part of the solar system inventory. Unlike regular satellites, the irregular moons revolve around planets at large distances in tilted and eccentric orbits. Their origin, which is intimately linked with the origin of the planets themselves, is yet to be explained. Here we report a study of the orbital and collisional evolution of the irregular satellites from times after their formation to the present epoch. The purpose of this study is to find out the features of the observed irregular moons that can be attributed to this evolution and separate them from signatures of the formation process. We numerically integrated ≈60,000 test satellite orbits to map orbital locations that are stable on long time intervals. We found that the orbits highly inclined to the ecliptic are unstable due to the effect of the Kozai resonance, which radially stretches them so that satellites either escape from the Hill sphere, collide with massive inner moons, or impact the parent planet. We also found that prograde satellite orbits with large semimajor axes are unstable due to the effect of the evection resonance, which locks the orbit's apocenter to the apparent motion of the Sun around the parent planet. In such a resonance, the effect of solar tides on a resonant moon accumulates at each apocenter passage of the moon, which causes a radially outward drift of its orbital apocenter; once close to the Hill sphere, the moon escapes. By contrast, retrograde moons with large orbital semimajor axes are long-lived. We have developed an analytic model of the distant satellite orbits and used it to explain the results of our numerical experiments. In particular, we analytically studied the effect of the Kozai resonance. We numerically integrated the orbits of the 50 irregular moons (known by 2002 August 16) for 108 yr. All orbits were stable on this time interval and did not show any macroscopic variations that would indicate instabilities operating on longer time spans. The average orbits calculated from this experiment were then used to probe the collisional evolution of the irregular satellite systems. We found that (1) the large irregular moons must have collisionally eliminated many small irregular moons, thus shaping their population to the currently observed structures; (2) some dynamical families of satellites could have been formed by catastrophic collisions among the irregular moons; and (3) Phoebe's surface must have been heavily cratered by impacts from an extinct population of Saturnian irregular moons, much larger than the present one. We therefore suggest that the Cassini imaging of Phoebe in 2004 can be used to determine the primordial population of small irregular moons of Saturn. In such a case, we will also better understand the overall efficiency of the formation process of the irregular satellites and the physical conditions that existed during planetary formation. We discovered two dynamical families of tightly clustered orbits within the Jovian retrograde group. We believe that these two clusters may be the remnants of two collisionally disrupted bodies. We found that the entire Jovian retrograde group and the Saturnian inclination groups were not produced by single breakups, because the ejection velocities derived from the orbital structures of these groups greatly exceed values calculated by modern numerical models of collisional breakups. Taken together, the evidence presented here suggests that many properties of the irregular moons previously assigned to their formation process may have resulted from their later dynamical and collisional evolution. Finally, we have found that several irregular moons, namely, Pasiphae, Sinope, S/2001 J10, S/2000 S5, S/2000 S6, and S/2000 S3, have orbits characterized by secular resonances. The orbits of some of these moons apparently evolved by some slow dissipative process in the past and became captured in tiny resonant volumes.

Implied Evolutionary Differences of the Jovian Irregular Satellites from a BVR Color Survey

We present BVR colors and magnitudes for four jovian irregular prograde satellites (Himalia J6, Elara J7, Lysithea J10, and Leda J13) and four irregular retrograde satellites (Pasiphae J8, Sinope J9, Carme J11, and Ananke J12). All eight have generally ‘solar’ colors but the retrograde group has slightly redder and more diverse colors. The strikingly similar colors of the four prograde satellites suggest the parent planetesimal was likely very homogeneous. The four retrograde satellites show a diversity in color that suggests a heterogeneous progenitor and thus variations in precapture formation history. The absolute magnitudes and revised diameters are presented. We also report new colors and diameters for two uranian irregular satellites (Caliban (S/1997 U1) and Sycorax (S/1997 U2) that are slightly redder than any of these jovian satellites.

Effects of hypothermic machine perfusion on rat liver function depending on the route of perfusion.

The aim of this study was to evaluate the efficacy of hypothermic machine perfusion (HMP) to preserve rat livers according to the route of perfusion, i.e., via portal vein, hepatic veins (retrograde), or hepatic artery. Livers were preserved for 24 or 48 hr by simple cold storage (SCS) or by HMP. Preservation solution was supplemented with (HMP) or without (SCS) hydroxyethyl starch. After preservation, grafts were reperfused for 2 hr with an oxygenated Krebs-Henseleit bicarbonate buffer. After 24 hr of preservation, total glutathione concentrations in HMP livers were similar (1287+/-37, 1418+/-118, and 1471+/-62 nmol/g in hepatic artery, portal vein, and hepatic vein HMP livers, respectively) and higher than in the SCS (833+/-118 nmol/g, P<0.05) group. These higher total glutathione values were due to higher reduced glutathione concentrations. ATP concentrations in the liver tissue were similar in HMP groups (0.75+/-0.4, 0.64+/-0.1, and 0.77+/-0.1 micromol/g in hepatic artery, portal vein, and hepatic vein HMP livers, respectively) and higher than in SCS (0.32+/-0.06 micromol/g, P<0.05). After 2 hr of normothermic reperfusion, bile production in the HMP portal and HMP retrograde groups were similar (391+/-29 ml and 372+/-25 ml) and higher than in the HMP artery or SCS groups (275+/-25 ml and 277+/-32 ml, respectively; P<0.05). Aspartate transaminase, alanine transaminase, lactate dehydrogenase, and purine nucleoside phosphorylase release into the perfusate of HMP portal and HMP retrograde perfused livers was similar and significantly lower compared to the HMP artery and SCS groups. At the end of reperfusion, no statistical differences were found for glutathione concentration and energetic reserves in the livers of each group. After 48 hr of preservation, livers from the HMP portal and HMP retrograde groups did significantly better than livers from the HMP artery or SCS groups. This study confirms the superiority of HMP over SCS to preserve the liver graft. It shows that retrograde perfusion is similar to PV perfusion and that perfusion by HA is less beneficial.

Cerebral protection selection in aortic arch surgery for patients with preoperative complications of cerebrovascular disease.

Retrograde perfusion is gaining acceptance as a means of cerebral protection, but it remains unclear how long the brain is protected and whether it is effective in patients with preoperative cerebrovascular disease. From January 1989 to August 1999, 205 patients--118 male and 87 female patients who ranged 12 to 86 years old, mean: 65.5 years old--underwent surgery at our hospital for aortic arch aneurysm using cerebral protection. We focused on mortality, stroke incidence and perioperative risk factor between 2 groups--selective cerebral and retrograde cerebral perfusion--also studying patients with preoperative cerebrovascular disease that influenced postoperative stroke. The hospital mortality was 11.7% (selective cerebral perfusion group: 12%, retrograde group: 10.9%). Stroke occurred in 11 patients (5.3%), 4.7% in the selective cerebral perfusion group and 7.3% in the retrograde group. Preoperative cerebrovascular disease does not appear to be a risk factor for postoperative brain damage in aortic arch surgery. Regarding total replacement of the aortic arch, the incidence of postoperative brain damage in the retrograde group with preoperative cerebrovascular disease was higher than that in another group (p = 0.072). Cardiopulmonary bypass time and selective cerebral perfusion time in the patients with postoperative stroke were significantly longer than that in non-stroke group. Preoperative cerebrovascular disease did not appear to be a risk factor in postoperative neurological deficit in the selective cerebral perfusion group. Prolonged selective cerebral perfusion time and cardiopulmonary bypass time may, however, lead to brain edema and cause neurological deficit.

Influence of different routes of flush perfusion on the distribution of lung preservation solutions in parenchyma and airways.

The present study was performed to investigate the influence of different routes of perfusion on the distribution of the preservation solutions in the lung parenchyma and upper airways. Pigs were divided into four groups: control (n = 6), pulmonary artery (PA) (n = 6), simultaneous PA + bronchial artery (BA) (n = 8), and retrograde delivery (n = 6). After preparation and cannulation, cardioplegia solution and Euro-Collins solution (ECS) for lung preservation were given simultaneously. After removal of the heart, the double lung bloc was harvested. Following parameters were assessed: total and regional perfusion (dye-labeled microspheres), tissue water content, PA, aorta, left atrial and left ventricular pressures, cardiac output and lung temperature. Our data show that flow of the ECS in lung parenchyma did not reach control values (9.4+/-1.0 ml/min per g lung wet weight) regardless of the route of delivery (PA 6.3+/-1.5, PA + BA 4.8+/-0.9, retrograde 2.7+/-0.9 ml/min per g lung wet weight). However, flow in the proximal and distal trachea were significantly increased by PA + BA delivery (0.970+/-0.4, respectively, 0.380+/-0.2 ml/min per g) in comparison with PA (0.023+/-0.007, respectively, 0.024+/-0.070 ml/min per g), retrograde (0.009+/-0.003, respectively, 0.021+/-0.006 ml/min per g) and control experiments (0.125+/-0.0018, respectively, 0.105+/-0.012 ml/g per min). Similarly the highest flow rates in the right main bronchus were achieved by PA + BA delivery (1.04+/-0.4 ml/min per g) in comparison with 0.11+/-0.03 in control, 0.033+/-0.008 in PA, and 0.019+/-0.005 ml/min per g in retrograde group. Flows in the left main bronchus were 0.09+/-0.02 ml/min per g in control, 0.045+/-0.012 ml/min per g in PA, and 0.027+/-0.006 ml/min per g in retrograde group. The flow rates were significantly (P = 0.001) increased by PA + BA delivery of the storage solution (0.97+/-0.3 ml/min per g). Our data show that the distribution of ECS for lung preservation is significantly improved in airway tissues (trachea and bronchi) if a simultaneous PA + BA delivery is used.

Myocardial protection during antegrade versus retrograde cardioplegia

Background. It has been suggested that the right ventricular myocardium is suboptimally protected during retrograde blood cardioplegia. Methods. Twenty patients undergoing an elective coronary bypass procedure were randomized to receive antegrade or retrograde mild hypothermic blood cardioplegia. Transventricular differences in oxygen extraction, lactate production, and pH were monitored during aortic cross-clamping, and myocardial biopsy specimens were taken from both ventricles before cannulation and 15 minutes after aortic declamping for analysis of adenine nucleotides and their breakdown products. The extent of myocardial injury was estimated by monitoring postoperative leakage of troponin T and the MB isoenzyme of creatine kinase. Hemodynamic recovery and postoperative complications were noted. Results. The preoperative characteristics of the two groups were similar. Oxygen extraction and lactate production in the right ventricular myocardium were higher in the retrograde group. In this group, the right ventricle also extracted more oxygen and produced more lactate and acid than did the left ventricle. Tissue levels of adenine nucleotides tended to decrease in both ventricles during operation, with no differences between them. The level of adenosine catabolites did increase somewhat in the right ventricular myocardium of the retrograde cardioplegia group after aortic declamping. There was a tendency for more prominent efflux of troponin T and the MB isoenzyme of creatine kinase in the retrograde group. Nevertheless, the postoperative course was uneventful in both groups. Conclusions. Retrograde mild hypothermic blood cardioplegia leads to metabolic changes compatible with right ventricular ischemia. Nevertheless, tissue levels of high-energy phosphates are well preserved, and the postoperative course seems to be unproblematic. Care should be taken when retrograde normothermic blood cardioplegia is provided for patients with right ventricular hypertrophy, poor right ventricular function, or severe preoperative myocardial ischemia.

Does Retrograde Administration of Blood Cardioplegia Improve Myocardial Protection During First Operation for Coronary Artery Bypass Grafting?

The objective of this study was to evaluate the value of retrograde blood cardioplegia in coronary artery bypass grafting. In 1994 and 1995, 224 patients undergoing first-time isolated coronary artery bypass grafting were randomized to antegrade (112 patients, group 1) or retrograde (112 patients, group 2) administration of blood cardioplegia. In group 1, 76 patients were given warm cardioplegia (at 33 degrees C) and 36 had cold cardioplegia (< 20 degrees C), whereas in group 2 cardioplegia was warm in 77 patients and cold in 35. The two randomization groups had similar demographic and angiographic characteristics. The number of grafted coronary arteries averaged 2.9 +/- 0.7 in group 1 and 2.8 +/- 0.7 in group 2. Total duration of cardiopulmonary bypass (78 +/- 23 and 75 +/- 21 minutes) and of aortic cross-clamping (47 +/- 16 and 46 +/- 16 minutes), total volume of infusion of the crystalloid component of cardioplegia (988 +/- 297 and 1016 +/- 595 mL), and total duration of infusion of cardioplegia (23 +/- 10 and 22 +/- 11 minutes) were similar (p > 0.05). There was no death in group 1 and one in group 2 as a result of a pulmonary embolus, for a global early mortality of 0.45%. The numbers of perioperative myocardial infarction (5 versus 3), congestive heart failure (4 versus 5), postoperative hemorrhage (4 versus 4), and stroke (1 versus 2) were also similar (p > 0.05). Release curves of total creatine kinase, creatine kinase-MB by serum activity and mass concentration, and troponin T were not significantly different (p > 0.05) between the two groups. For the 216 patients without perioperative myocardial infarction, peak enzyme release of creatine kinase-MB at 24 hours averaged 23 +/- 22 and 20 +/- 18 IU/L, and that of troponin T averaged 1.1 +/- 1.1 and 1.3 +/- 1.5 micrograms/L at 6 hours for the antegrade and the retrograde groups, respectively (p > 0.05). Our results indicate no evidence that the retrograde method of cardioplegic infusion improves myocardial protection during first operation for isolated coronary revascularization compared with the usual antegrade route.

Evaluation of 7,000 Patients With Two Different Routes of Cardioplegia

Background. This study examined the efficacy and safety of retrograde cardioplegia in comparison with an antegrade/retrograde approach.Methods. Between January 1, 1991, and December 31, 1995, 7,032 coronary artery bypass procedures, alone or in combination with valve replacement/repair, were performed using either retrograde cardioplegia (R) or an antegrade/retrograde (AR) approach. There were 4,224 patients in the R group and 2,808 in the AR group. These included elective, urgent, emergent/salvage, first operative, and redo cases.Results. All preoperative, intraoperative, and postoperative variables listed in The Society of Thoracic Surgeons National Cardiac Surgery Database were used to compare the two groups using univariate analysis. The pump time was longer in the AR group, with fewer grafts per patient. The R group had higher predicted risk (3.2% versus 3.0%; p = 0.04), more postoperative atrial fibrillation (34% versus 31%; p = 0.006), and longer postoperative length of stay (8.8 versus 8.0 days; p < 0.001). Using The Society of Thoracic Surgeons National Cardiac Surgery Database predicted risk group model, a subgroup of 221 coronary artery bypass grafting patients in the retrograde (s-R) and 132 coronary artery bypass grafting patients in the antegrade/retrograde (s-AR) group fell into a greater incidence of predicted mortality group (≥10%). The s-R subgroup had more patients in New York Heart Association functional class IV. Univariate analysis revealed higher postoperative atrial fibrillation (51% versus 41%; p = 0.05) and longer postoperative length of stay (12.8 versus 10.8 days; p = 0.03) in the s-R subgroup versus the s-AR subgroup.Conclusions. The results appear to favor neither approach. Preoperatively, both retrograde groups (R and s-R) had higher preoperative predicted risk, but operative mortality or complications were not significantly increased when compared with the AR and s-AR groups. Retrograde cardioplegia alone was shown to be effective in the R and s-R groups, but atrial fibrillation developed in more patients, which could have contributed to longer length of stay in these groups. Antegrade/retrograde cardioplegia offers good immediate outcome but the delivery method can be cumbersome and confusing during the adjustments of flow clamps for antegrade/retrograde delivery and may contribute to prolonged pump times. From this retrospective, nonrandomized review, it appears that retrograde cardioplegia alone provides as good myocardial protection and safety as an antegrade/retrograde approach in either the low-risk or high-risk patient.(Ann Thorac Surg 1997;63:1619–24)

Cerebral protection during moderate hypothermic circulatory arrest: Histopathology and magnetic resonance spectroscopy of brain energetics and intracellular pH in pigs

Objective: We evaluated the effect of antegrade and retrograde brain perfusion during moderate hypothermic circulatory arrest at 28º C. Methods: Phosphorus 31–magnetic resonance spectroscopy was used to follow brain energy metabolites and intracellular pH in pigs during 2 hours of ischemia and 1 hour of reperfusion. Histopathologic analysis of brain tissue fixed at the end of the experimental protocol was performed. Fourteen pigs were divided into two experimental groups subjected to antegrade ( n = 6) or retrograde ( n = 8) brain perfusion. Anesthesia ( n = 8) and hypothermic cardiopulmonary bypass groups (15º C, n = 8) served as control subjects. In the antegrade and retrograde brain perfusion groups, the initial bypass flow rate was 60 to 100 ml · kg -1 · min -1. In the antegrade group, the brain was perfused through the carotid arteries at a flow rate of 180 to 210 ml · min -1 during circulatory arrest at 28º C. In the retrograde group, the brain was perfused through the superior vena cava at a flow rate of 300 to 500 ml · min -1 during circulatory arrest at 28º C. Results: The intracellular pH was 7.1 ± 0.1 and 7.2 ± 0.1 in the anesthesia and hypothermic bypass groups, respectively. Brain intracellular pH and high-energy metabolites (adenosine triphosphate, phosphocreatine) did not change during the course of the 3.5-hour study. In the antegrade group, adenosine triphosphate and intracellular pH were unchanged throughout the protocol. In the retrograde perfusion group, the intracellular pH level decreased to 6.4 ± 0.1, and adenosine triphosphate and phosphocreatine levels decreased within the first 30 minutes of circulatory arrest and remained at low levels until the end of reperfusion. High-energy phosphates did not return to their initial levels during reperfusion. Histopathologic analysis of nine regions of the brain showed good preservation of cell structure in the anesthesia, hypothermic bypass, and antegrade perfusion groups. The retrograde perfusion group showed changes in all the regions examined. Conclusions: The study shows that moderate hypothermic circulatory arrest at 28º C with antegrade brain perfusion during circulatory arrest protects the brain but that retrograde cerebral perfusion at 28º C does not protect the brain. (J T HORAC C ARDIOVASC S URG 1996;112:1073-80)

Protection of the right ventricle: comparison of retrograde with antegrade cardioplegia

The adequacy of right ventricular (RV) preservation and cooling with retrograde cardioplegia has been questioned. We compared the effects of retrograde with antegrade cardioplegia on the recovery ventricular function inpatients undergoing coronary artery surgery. Two groups of similar age, left ventricular function and extent of disease received either retrograde (RC) or antegrade (AC) multidose cold-blood cardioplegia. A right ventricular rapid-response catheter measured right ventricular haemodynamics before and after bypass. Needle thermistors recorded intramyocardial temperatures in the right ventricular free wall, the left ventricular free wall and the septum. There were no differences in bypass times, ischaemic times, inotrope requirements or arrhythmia frequency between the 2 groups. RV haemodynamics were similar in both groups before bypass. Immediately after bypass the RV end diastolic volume index was lower in the retrograde group than in the antegrade group, and RV ejection fraction was higher. This indicates better RV preservation with retrograde cardioplegia early after bypass. By 30 min after bypass all haemodynamic variables had returned to baseline values in both groups. Retrograde cardioplegia provided effective cooling in all areas of the heart. The mean time to achieve electromechanical quiescence was longer with retrograde cardioplegia, and a larger total volume of cardioplegia was required. Except for a minor advantage for RC soom after bypass, this study suggests that RV protection during coronary artery surgery is the same whether retrograde or antegrade cardioplegia is used. The time taken o achieve diastolic arrest with retrograde cardioplegia may presuade surgeons that combination of antegrade and retrograde cardioplegia remains the most satisfactory technique.

Clinical trial of retrograde warm blood reperfusion versus standard cold topical irrigation of transplanted hearts

A prospective, randomized clinical study involving 34 patients undergoing heart transplantation compared myocardial preservation of donor hearts maintained with continuous reperfusion with retrograde warm blood cardioplegia during surgical implantation versus the standard cold topical irrigation. Hearts in both groups were arrested with a standard crystalloid solution and maintained in a cold saline solution during transportation. In the retrograde group, cardioplegia was administered through a catheter in the coronary sinus during surgical implantation. An average of 471 +/- 30 mL of hyperkalemic crystalloid solution diluted 1:4 in warm blood from the oxygenator was infused. In the standard group, the heart was kept cold by topical irrigation of cold saline solution and was reperfused only when the ascending aorta was unclamped. Preoperative characteristics of donors and recipients were similar in the two cohorts. Ischemic time average 139 +/- 12 minutes in the retrograde group compared with 130 +/- 11 minutes in the standard group (p = 0.57). Cardiopulmonary bypass time averaged 89 +/- 4 minutes in the retrograde group and 110 +/- 12 minutes in the standard group (p = 0.12). Defibrillation at reperfusion was performed in 4 patients (4/17, 24%) in the retrograde group and 12 patients (12/18, 67%) in the standard group (p = 0.01). There were no deaths in the retrograde group (0/17), whereas in the standard group, 3 patients (3/17) died of early graft failure (p = 0.11). Four early graft failures occurred in the standard group (p = 0.06). Two patients (2/17, 12%) were weaned from bypass with ventricular assist devices in the standard group. The number of subendocardial necrotic cells in the first two weekly endomyocardial biopsy specimens averaged 2.7 +/- 0.8 cells/mm2 in the retrograde group and 5.9 +/- 2.4 cells/mm2 in the standard group (p = 0.12). Retrograde warm blood reperfusion appears to improve the initial recovery of transplanted hearts. The technique is easy to use and may be a useful approach to graft protection during surgical implantation.

The effect of retrograde cerebral perfusion after particulate embolization to the brain

Neurologic injury as a consequence of cerebral embolism of either air or atherosclerotic debris during cardiac or aortic surgery is still a major cause of postoperative morbidity and mortality. While exploring various means of improving cerebral protection during complex cardiothoracic procedures, we have developed a chronic porcine model to study retrograde cerebral perfusion. We have previously demonstrated that retrograde perfusion results in a small amount of nutritive flow and provides cerebral protection that appears to be superior to simple prolonged hypothermic circulatory arrest. The current study was designed to evaluate the efficacy of retrograde cerebral perfusion in mitigating the effects of particulate cerebral embolism occurring during cardiac surgery. Four groups of pigs (19 to 28 kg) underwent cardiopulmonary bypass with deep hypothermia at an esophageal temperature of 20°C: an antegrade control group (AC, n = 5), an antegrade embolism group (AE, n = 10), a retrograde control group (RC, n = 5), and a retrograde embolism group (RE, n = 10). In addition, because of extreme heterogeneity in outcome in the initial RE group, an additional group of 10 animals underwent embolism and retrograde perfusion at a later time. Embolization was accomplished by injection of 200 mg of polystyrene microspheres (250 to 750 μg in diameter) via the aortic cannula into an isolated aortic arch preparation in the AE and RE groups; the control groups received injections of 10 ml of saline solution. After infusion of the microspheres or saline solution, conventional perfusion, with the aortic arch pressure maintained at 50 mm Hg, was continued for a total of 30 minutes in the antegrade groups; in the retrograde groups, retrograde flow was initiated via a cannula positioned in the superior vena cava, and was continued for 25 minutes. Superior vena caval flow was regulated to maintain a sagittal sinus pressure of approximately 30 mm Hg in the retrograde groups, and blood returning to the isolated aortic arch was collected and measured. All animals were allowed to recover and were evaluated daily according to a quantitative behavioral score in which 9 indicates apparently complete normalcy, with lower numbers indicating various degrees of cerebral injury. At the time of planned death on day 6, half of the brain was used for recovery of embolized microspheres after digestion with 10N sodium hydroxide. The other half was submitted for histologic study. Neurologic recovery in both the antegrade and retrograde control groups appeared to be complete, although mild evidence of histologic damage was present in some animals in the retrograde control group. After embolization, unequivocal neurologic injury occurred in both groups, accompanied by significant cerebral histopathologic abnormalities. Although neurologic outcome was not significantly better in the initial RE group as a whole than in the AE group, it was noted that several of the RE animals recovered almost completely after retrograde cerebral perfusion (behavioral scores >7). The animals with good behavioral recovery were noted to have been perfused with markedly lower superior vena caval pressures than those used in animals that sustained severe neurologic injury. An additional 10 animals were therefore subjected to embolization and retrograde perfusion to clarify the impact on outcome of different superior vena caval pressures during retrograde perfusion. When these additional animals are included in the analysis, the behavioral and neuropathologic evidence suggests that use of retrograde cerebral perfusion may attenuate the severity of cerebral injury resulting from particulate emboli when adequate retrograde perfusion can be maintained at low superior vena caval pressures (<40 mm Hg). This observation merits further study. (J T HORAC C ARDIOVASC S URG 1995;110:1470-85)

A 31P-magnetic resonance study of antegrade and retrograde cerebral perfusion during aortic arch surgery in pigs

To evaluate the effect of hypothermic circulatory arrest on brain metabolism, we used 31P-magnetic resonance spectroscopy to monitor brain metabolites in pigs during 2 hours of ischemia and 1 hour of reperfusion. Twenty-eight pigs were divided into five groups. Anesthesia (n = 5) and hypothermic cardiopulmonary bypass groups (n = 5) served as controls. In the circulatory arrest (n = 6), antegrade perfusion (n = 6), and retrograde (n = 6) brain perfusion groups, the bypass flow rate was 60 to 100 ml.kg-1.min-1. In the antegrade group, the brain was perfused via the carotid arteries at a blood flow rate of 180 to 200 ml.min-1 during circulatory arrest at 15 degrees C. In the retrograde group, the brain was perfused through the superior vena cava at a flow rate of 300 to 500 ml.min-1 during circulatory arrest at 15 degrees C. The intracellular pH was 7.1 +/- 0.1 and 7.3 +/- 0.1 in the anesthesia and hypothermic cardiopulmonary bypass groups, respectively. In the circulatory arrest group, the intracellular pH decreased to 6.2 +/- 0.1 and did not recover to its initial value (7.0 +/- 0.1) during reperfusion (p < 0.05 compared with the value obtained from the control groups at the corresponding time). Inorganic phosphate did not return to its initial level during reperfusion. In three animals in this group, levels of high-energy phosphates, adenosine triphosphate and phosphocreatine, recovered partially but did not reach the levels observed before arrest. In the group receiving antegrade perfusion, cerebral metabolites and intracellular pH were unchanged throughout the protocol. During circulatory arrest in the retrograde perfusion group the intracellular pH decreased to 6.4 +/- 0.1 and recovered fully during reperfusion (7.1 +/- 0.1). High-energy phosphates also returned to their initial levels during reperfusion. These studies show that deep hypothermic circulatory arrest with antegrade brain perfusion provides the best brain protection of the options investigated.

Antegrade versus Retrograde Cardioplegia for Uncomplicated Coronary Artery Disease: A Comparative Study

Since the introduction of the retrograde administration of cardioplegic solutions in cardiac surgery in the mid-1980's, the technique has been widely adopted for routine use in high risk patients with impaired ventricular function, based on favorable results demonstrated in clinical series. However, we sought to evaluate the benefits of routine use of this method in low risk patients by means of a retrospective review of 34 consecutive non-repeat, isolated coronary artery bypass grafting patients with left ventricular ejection fractions &gt; 35%. Seventeen patients received intermittent ante grade cardioplegia exclusively and 17 received ante grade induction followed by intermittent retrograde cardioplegia maintenance. No significant baseline differences were found between the two groups. There were no deaths or major complications in either group. Retrograde cardioplegia patients had significantly lower pulmonary artery diastolic pressures in the first 24 hours postoperatively, accompanied by a non-significant trend toward higher cardiac indices during this same period. Phenylephrine infusions were used more frequently during the postoperative period in the retrograde group (p = 0.021). Fewer pulmonary complications were seen in the retrograde cardioplegia group (p=0.042), in addition to non-significant trends toward less atrial arrhythmias and less hospital days. No adverse effects or increased operative time could be attributed to the retrograde administration of cardioplegic solution in this study population. Based on the results from this small clinical series, retrograde cardioplegia administration offers distinct advantages for myocardial protection in low risk coronary bypass patients, as manifested by improved postoperative hemodynamic performance, with no significant adverse effects. A prospective, randomized trial of this technique in a larger, similar patient population is likely to show even more compelling positive results favoring the routine use of retrograde administration of cardioplegic solutions.

Cerebral microemboli during coronary artery bypass using different cardioplegia techniques

Larger numbers of microemboli detected by transcranial Doppler echocardiography have been linked to adverse neuropsychological outcome after coronary artery bypass grafting. Differences in neurologic outcome have been attributed to different cardioplegia techniques. Transcranial Doppler-detected microembolic events were recorded during coronary artery bypass grafting using different cardioplegia techniques. Patients received cold antegrade (n = 20), warm antegrade (n = 17), or warm retrograde (n = 20) cardioplegia. Continuous monitoring was divided into stages: aortic cannulation, initiation of cardiopulmonary bypass, aortic cross-clamping, aortic declamping and decannulation until chest closure. Rate of embolic events and number of total and immediate embolic events were tabulated. Total embolic events ranged from 22 to 2,072 per patient and were similar among groups. The rate and total at each stage were similar. Total embolic events were highest during aortic clamping; the rate was highest at initiation of bypass. The immediate embolic events were higher in the warm retrograde group than both antegrade groups at aortic declamping. In summary, a high total and rate of embolic events were detected and differences between cardioplegia techniques were detected.